[Closed] accessing ui elements from function triggered by callback

I’m trying to update my UI whenever a new file is opened.
I use the #filePostOpen callback and this triggers a function.

The problem I’ve got is that I cannot access the UI from the function.
I guess I’m missing something obvious here.
I tried to define the “lbl1” as a global, but that did not help.

I’ve stripped down the script to this easy test, run it – then open a scene.

fn refreshGUICallback =
(
	print "this is inside the test function..."
	lbl1.text = "Label updated from function, success."
)

rollout callbackUI "callback example" width:160 height:130
(
	label lbl1 "supposed to be updated from callback function, open a file to trigger callback." pos:[8,8] width:144 height:71
)


callbacks.removeScripts id:#refreshGUICallback
callbacks.addScript #filePostOpen "refreshGUICallback()" id:#refreshGUICallback

MainUIFloater = newrolloutFloater "callback example" 180 140
addrollout callbackUI MainUIFloater

when you run it you get this error when opening a file:

---------------------------
MAXScript Callback script Exception
---------------------------
-- Unknown property: "text" in undefined
---------------------------
OK   
---------------------------